2. 1. What is it? 2. What is the main cause of it? 3. What chemical reactions are involved? 4. What are the effects of it? 5. What can we do about it?

3. pH related to the exponent of molarity of [H 3 O + ] Examples: Concentration of H 3 O + is 1.0 × 10 –1 M  pH =1 Concentration of H 3 O + is 1.0 × 10 –5 M  pH =5 Concentration of H 3 O + is 1.0 × 10 –8 M  pH =8 Every 1.0 drop in pH = ten times higher [H 3 O + ] pH = 7.0  [H 3 O + ] = 1/10,000,000 moles per liter pH = 6.0  [H 3 O + ] = 1/1,000,000 moles per liter pH = 1.0  [H 3 O + ] = 1/10 moles per liter [H 3 O + ] at pH 1 is million X higher than at pH 7 Review- pH Scale

4. pH Scale pH of Selected natural liquids Ocean water 8.0 – 8.2 (varies by location & time) Human blood 7.35 – 7.45 Pure water 7.0 At 25°C both [H 3 O + ] and [OH – ] is 1.0 × 10 –7 M “Clean” rain 5.6 – 5.7 “Acid” rain is defined as anything with pH <5.0

5. Atmosphere behaves much like human blood. Both have CO 2 gas which can dissolve in water After dissolving, CO 2 reacts with water to form carbonic acid - a weak acid. CO 2 + H 2 O H 2 CO 3 Carbonic acid and bicarbonate ions form an important pH buffer [H 2 CO 3 + H 2 O HCO 3 - + H 3 O + ] “Clean” rain typically has pH 5.6 - 5.7 About 15 times [H 3 O + ] of pure water Why “Clean” Rain is slightly acidic

6. Formed from anthropogenic sources (i.e. human activity) SO 2 gas - released primarily from burning coal SO 2 reacts with water through a series of reactions to form sulfuric acid – a strong acid. SO 2 + H 2 O H 2 SO 4 NO 2 gas - released primarily from internal combustion engines burning gasoline and diesel fuel NO 2 reacts with water to form nitric acid (a strong acid) and nitrous acid (a weak acid) 2NO 2 + H 2 O HNO 3 + HNO 2 Causes of “Acid Rain”

7. Forests, freshwaters and soils become more acidic Trees lose nutrients, poisoned, susceptible to attack by insects, fungus, etc. Insect and aquatic life-forms (especially fish) struggle and die Some lakes in New England had no non-algae life in mid- 80’s Manmade structures are also impacted Damage to buildings and sculptures made of stone Adverse Impacts of “Acid Rain”

8. “Acid” rain pH < 5.0 Typically 5 - 20 times [H 3 O + ] of “normal” rain with pH = 5.7 Acid Rain video clip made by students: http://www.youtube.com/watch?v=8 93KB3s_jIA&feature=related http://www.youtube.com/watch?v=8 93KB3s_jIA&feature=related

9. Trees killed by acid rain GNU Free Documentation License Video clip - What’s eating Washington D.C http://www.youtube.com/watch?v= MqHw1hMEkAQ&feature=fvst http://www.youtube.com/watch?v= MqHw1hMEkAQ&feature=fvst

10. Acid rain can eat through stone and metal. Accelerated weathering process on stone angel's face. Photographer: Michael Drager | Agency: Dreamstime.comDreamstime.com

11. Coal Combustion & Acid Rain 2007-03-01 03:49 Analogue Kid 2048×1536×8 (868607 bytes) The General James M. Gavin plant on the Ohio River. Note the clouds of water and Sulfuric Acid coming from the stacks (the emissions from the Cooling Towers are just water vapor). Self made photo.Analogue Kid Video Clip about Cleaning Up Coal Technology http://www.youtube.com/watch?v=H E6Y0iEuXMQ&feature=fvwrel http://www.youtube.com/watch?v=H E6Y0iEuXMQ&feature=fvwrel

12. How to Stop Acid Rain Tighter emissions regulation for power generation Capture more SO 2 and other pollutants Use alternative energy sources Transportation improvements Catalytic converters to reduce NO 2 Hybrids and alternative power sources Improved mpg standards

13. 1. What is it? 2. What is the main cause of it? 3. What chemical reactions are involved? 4. What are the effects of it? 5. What can we do about it?